[Brian]

Happy to help! The calendar file is updated during OmniFocus' sync process, so launching the app isn't by itself sufficient. (Unless the launch triggers an auto-sync, I suppose.)

The MobileMe calendar sync process doesn't know anything about OmniFocus' database, so a MobileMe calendar sync can't change the actions inside the app. OmniFocus does the work of reading in the calendar file, making any necessary changes to the OF database, and then pushing a new calendar file up to the server.